Manufacture of artificial filaments and other products containing organic derivatives of cellulose



. of acetone per 100 parts of water.

Patented Feb. 16, 1937 UNETED STATES PATENT OFFICE Percy Frederick Combs Sowter, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application February 9,

In Great Britain February Serial No. 5,867. 21, 1934 Claims.

This invention relates to the manufacture of artificial filaments, threads, yarns, ribbons and other products containing cellulose acetate or other organic derivative of cellulose and particularly to their manufacture by wet spinning processes.

In U. S. Patents Nos. 1,465,994 and 1,467,493 processes for the production of artificial products by wet spinning methods are described, according to which coagulating media containing solvents for the cellulose derivative are employed, U. S. Patent No. 1,467,493 describing the use, for example, of aqueous baths containing -50 parts Further, British Patent No. 340,324, describes wet spinning processes for the production of artificial products wherein the shaped materials are coagulated in media containing high concentrations of solvents for the cellulose derivatives concerned, particularly solvents which are less volatile than the non-solvents present in the coagulating media, and British Patent No. 340,325, describes a similar process employing plasticizing agents. By the processes described in the above specifications, and .particularly in British Patents Nos. 340,324 and 340,325, the artificial products, especially artificial filaments and the like, may be stretched to a considerable extent during their production, and products having a high tensile strength and of 10W denier may be obtained.

It has now been discovered that artificial filaments, threads and other products containing an organic derivative of cellulose and having a good tenacity and improved extensibility may be obtained by wet spinning processes in which the shaped materials are coagulated in a coagulating medium containing a solvent or plasticizer for the cellulose derivative, are stretched and are then allowed to shrink between the draw roller or other stretching device and the take-up device under the action of the solvent or plasticizer. Stretching and shrinkage may take place in the coagulating bath itself and/or after emergence from such bath under the action of the coagulating medium carried over by the materials.

In this manner a. shrinkage may be obtained which is, for example, of the order of 5-l0%, and a product may be produced having improved properties, particularly as regards extensibility.

The invention is of particular value in relation to the production of artificial filaments, threads and other products having a basis of cellulose acetate, but it may also be employed in ample cellulose propionate, butyrate, acetate-propionate, nitro-acetate or other ester or mixedester of cellulose, methyl, ethyl or butyl cellulose or other ether or mixed ether of cellulose or a mixed ether-ester of cellulose, for example ethyl cellulose acetate or oxy-ethyl cellulose acetate. The cellulose derivative may be of low or normal viscosity or of a high viscosity. For example, a cellulose acetate having a normal viscosity of about 12, or may be employed or one having a high viscosity, for example 40, 80, 100 or 200 or even more, the viscosity being calculated by comparison of a 6% solution of the cellulose acetate in acetone at C. compared with glycerine taken as 100. Processes for the production of such high viscosity cellulose derivatives are described in U. S. Patent No. 1,708,787 of Dr. Henry Dreyfus.

The solvents employed in the manufacture of the spinning solutions may be volatile, for example acetone, methylene ethylene ether, dioxane, mixtures of methylene or ethylene chloride with methyl or ethyl alcohol, or methyl or ethyl acetate with methyl or ethyl alcohol, or solvents of medium or low volatility may be employed, for example diacetone alcohol, ethyl lactate, glycol mono-acetate, methyl glycol mono-acetate and homologues and/or substitution products of dioxane, methylene ethylene ether and other cyclic ethers, for example alkylated dioxanes. Mixtures of solvents may be employed, for example a mixture containing a volatile solvent and a solvent of medium or low volatility.

The solvent present in the coagulating bath may be a volatile solvent or a solvent of medium or low volatility, for example any of those mentioned in the preceding paragraph, or mixtures of solvents may be employed, for example a mixture of a volatile solvent and a solvent of medium or low volatility. Preferably, however, the solvent employed is one of low volatility, for example diacetone alcohol, ethyl lactate, glycol mono-acetate or methyl glycol mono-acetate.

Preferably a coagulating bath containing a high concentration of solvent is employed, for example, an aqueous bath containing of diacetone alcohol and 15% of acetone or containing 45% of ethyl lactate.

The following is an example of one method of carrying out the process of the present inventi0n:--

Ewample A solution of cellulose acetate of about 25-26% concentration in acetone is extruded through suitable orifices into an aqueous coagulating medium desired after-treatment processes. For example,

'filaments, ribbons and other materials having a they may be again stretched in order still further to increase their tenacity, e. g. as described in British Patents Nos. 370,430 and 371,461, or may be subjected tofurther shrinking operations to improve their extensibility or for the production of shrinkage or other effects, as described, for example, inBritish Patents Nos. 389,- 823 and 380,504 and U. S. Patent No. 2,020,303. Again, they may be saponified, and the degreeof saponification may be relatively small, for example 10-20%, in order to give them an affinity for cotton dyestuffs, or it may be considerably more,

e. g. 40-60%, or complete or substantiallycomplete' saponification may be eifecte d so that arti-, ficial materials having a basis of regenerated cellulose are obtained. Examples of suitable saponification processes are described in British Patents Nos. 402,104 and 402,105. Further, saponification may be effected so that the outer layers of the materials only are saponified or so that a uniform saponification throughout the materials is effected.

What I claim and'desire to secure by Letters Patent is:

1. In a process for the manufacture of artificial filaments, ribbons and other materials having a basis'of organic derivatives of cellulose by wet spinning processes; the steps of coagulating the shaped materials in a coagulating 'medium containing a softening agent for the cellulose derivative, stretching the materials and then allowing the wet materialsto shrink under the action of the softening agent. a a

2. In a process for themanufacture of artificial filaments, ribbons and like filamentary materials having a basis of cellulose acetate bywetspining processes, the steps of coagulating the shaped materials in a coagulating medium containing a softening agent for the cellulose acetate, stretching the materials and then allowing the wet materials to shrink under the action of the softening agent.

3. In a processfor the manufactureof artificial basis of organic derivatives of cellulose by wet shaped materials in an aqueous coagulating medium containing a concentration of at least theorder of 45% of a softening agent for the cellulose derivative, stretching'the materials and then allowing the wet materials to shrink under the action of the softening agent.

4. In a process for the manufacture of artificial filaments, ribbons and like filamentary materials having a basis of organic derivatives of cellulose by wet spinning processes, the steps of coagulating the shaped materials in an aqueous coagulating medium containing a softening agent for the cellulose derivative of lower volatility than water,

stretching the materials and then allowing the wet materials to shrink under the action of the cellulose derivative, stretching the materials and then allowing the wet materials to shrink under the action of the softening agent by 5-10% of their length after stretching.

6. In a'process for the manufacture-of artificial filaments, ribbons and like filamentary materials having a'basis of organic derivatives of cellulose by wet spinning processesthe steps of coagulating the shaped materials in an aqueous coagulating medium containing a concentration of at least the order of 45% of a softening agent for the cellulose derivative of lower volatility than water, stretching the materials and then allowing the wet materials to shrink under the action of the softening agent by:5-10% of theirlength after stretching.

"I. In a process for the manufacture of artificial filaments, ribbons and like filamentary materials having a basis of cellulose acetate by wet spinning processes, the steps of coagulating the shaped materials in an aqueous coagulating medium containing diacetone alcohol ina concern tration of at least 45%, stretching the materials and then allowing the wet materials to shrink under the action of the diacetone alcohol. 7

8. In a process for the'manufacture of artificial filaments, ribbons and like filamentary materials having a basis of cellulose acetate by wet spinning processes, the steps of coagulating the shaped materials in an aqueous coagulating' medium. containing ethyl lactate in a concentra'-' tion of at least stretching the materials and then' allowing the wet'materials to shrink under the action of the ethyl lactate.

9. In a process for the manufacture of artificial filaments, ribbons and like filamentary materials having a basis of cellulose acetate by wet spinning processes, the steps of coagulating the shaped materials in an aqueous coagulating the order'of 45% of a softening agent forthe cellulose acetate, selected from the group con.- sisting of glycol mono-acetate and methyl glycol mono-acetate, stretching the materials and then allowing the wet materials to shrink under the action of the softening agent.

PERCY FREDERICK COMIBE SOWTER.

, medium containing a concentration of at least of 

